Dependence Levels as Interim Clinical Milestones Along the Continuum of Alzheimer's Disease: 18-Month Results from the GERAS Observational Study.

BACKGROUND: While functional loss forms part of the current diagnostic criteria used to identify dementia due to Alzheimer's disease, the gradual and progressive nature of the disease makes it difficult to recognize clinically relevant signposts that could be helpful in making treatment and management decisions. Having previously observed a significant relationship between stages of functional dependence (the level of assistance patients require consequent to Alzheimer's disease deficits, derived from the Alzheimer's Disease Cooperative Study - Activities of Daily Living Scale) and cognitive severity, we investigated whether measures of functional dependence could be utilized to identify clinical milestones of Alzheimer's disease progression. OBJECTIVES: To describe the patterns of change in dependence over the course of 18 months in groups stratified according to cognitive Alzheimer's disease dementia severity (determined using the Mini-Mental State Examination score) and to identify characteristics associated with patients showing worsening dependence (progressors) versus those showing no change or improvement (non-progressors). DESIGN: Analysis of longitudinal data from the GERAS study. SETTING: GERAS is an 18-month prospective, multicenter, naturalistic, observational cohort study reflecting the routine care of patients with Alzheimer's disease in France, Germany, and the United Kingdom. PARTICIPANTS: 1495 community-living patients, aged ≥55 years, diagnosed with probable Alzheimer's disease dementia, and their caregivers. MEASUREMENTS: Dependence levels, cognitive function, behavioral symptoms, caregiver burden, and cost were assessed at baseline and at 18 months. RESULTS: Of 971 patients having both baseline and 18-month data, 42% (408) were progressors and 563 (58%) were non-progressors. This general pattern held for all three levels of baseline Alzheimer's disease dementia severity - mild (Mini-Mental State Examination score 21-26), moderate (15-20) or moderately severe/severe (<15) - with 40-45% of each group identified as progressors and 55-60% as non-progressors. No baseline differences were seen between progressors and non-progressors in cognitive scores or behavioral symptoms, although progressors had significantly shorter times since diagnosis and showed milder functional impairment. Baseline factors predictive of increasing dependence over 18 months included more severe cognitive impairment, living with others, and having multiple caregivers. A higher level of initial dependence was associated with less risk of dependence progression. Total societal costs of care also increased with greater dependence. CONCLUSIONS: In this large cohort, 42% of Alzheimer's disease dementia patients at all levels of cognitive severity became more dependent within 18 months of observation while 58% did not progress. Dependence levels may be considered as meaningful interim clinical milestones that reflect Alzheimer's disease-related functional deficits, although a time frame that extends beyond 18 months may be necessary to observe changes if used in clinical trials or other longitudinal studies. Recognition of predictors of greater dependence offers opportunities for intervention.

Clinical and Economic Characteristics of Milestones along the Continuum of Alzheimer's Disease: Transforming Functional Scores into Levels of Dependence.

BACKGROUND: Because Alzheimer's disease (AD) is characterized by a gradual decline, it can be difficult to identify distinct clinical milestones that signal disease advancement. Adapting a functional scale may be a useful way of staging disease progression that is more informative for healthcare systems. OBJECTIVES: To adapt functional scale scores into discrete levels of dependence as a way of staging disease progression that is more informative to care providers and stakeholders who rely on the functional impact of diseases to determine access to supportive services and interventions. DESIGN: Analysis of data from the GERAS study. SETTING: GERAS is an 18-month prospective, multicenter, naturalistic, observational cohort study reflecting the routine care of patients with AD in France, Germany, and the United Kingdom. PARTICIPANTS: Data were from baseline results of 1497 community-living patients, aged ≥55 years, diagnosed with probable AD and their caregivers. MEASUREMENTS: We used data from the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory (ADCS-ADL) and mapped items onto established categories of functional dependence, validated using clinical and economic measures. Cognitive function, behavioral symptoms, caregiver burden, and cost were assessed. Based on stages of functional dependence described by the Dependence Scale, individual ADCS-ADL items were used to approximate 6 dependence levels. RESULTS: There was a significant relationship between assigned level of dependence derived from the ADCS-ADL score and cognitive severity category. As the assigned level of dependence increased, the associated clinical and economic indicators demonstrated a pattern of greater disease severity. CONCLUSIONS: This mapping provides initial support for dependence levels as appropriate interim clinical milestones that characterize the functional deficits associated with AD.

Analysis of burden in caregivers of people with Alzheimer's disease using self-report and supervision hours.

OBJECTIVES: This study aimed to describe the baseline characteristics of informal carers of community-living Alzheimer's disease (AD) patients by AD severity group and to identify factors associated with two measures of caregiver burden. DESIGN AND SETTING: GERAS is a prospective observational study in France, Germany, and the UK, designed to assess costs and resource use associated with AD, for patients and their caregivers, stratified by disease severity. PARTICIPANTS: 1497 community-dwelling AD patients and their primary caregivers. MEASUREMENTS: Subjective caregiver burden assessed using the Zarit Burden Interview [ZBI] and time spent supervising patients (an objective measure of burden recorded using the Resource Utilization in Dementia instrument) during the month before the baseline visit were recorded. Separate multiple linear regression analyses using ZBI total score and caregiver supervision time as dependent variables were performed to identify patient and caregiver factors independently associated with caregiver burden. RESULTS: Increasing AD severity was associated with both subjective caregiver burden (ZBI total score) and overall caregiver time, which includes supervision time (both p<0.001, ANOVA). Better patient functioning (on instrumental activities of daily living) was independently associated with both a lower ZBI total score and less supervision time, whereas higher levels of caregiver distress due to patient behavior were associated with greater caregiver burden. Other factors independently associated with an increased ZBI total score included younger caregiver age, caregiver self-reported depression, caring for a male patient, and longer time since AD diagnosis. Caregivers living with the patient, being a male caregiver, patient living in a rural location, higher patient behavioral problem subdomain scores for apathy and psychosis, more patient emergency room visits, not receiving food delivery and receiving financial support for caregiving were all associated with greater caregiver supervision time. CONCLUSION: Our results show that subjective caregiver burden and caregiver time are influenced by different factors, reinforcing the need to consider both aspects of caregiving when trying to minimize the burden of AD. However, interventions that minimize caregiver distress and improve patient functioning may impact on both subjective and objective burden.